Reciprocating piston engine

ABSTRACT

A reciprocating piston engine is disclosed having a first inner magnetic field unit comprising a first inner magnetic field unit arranged on a first crank arm of a crankshaft including a magnetizable material, and a stationary first outer magnetic field unit. The first inner magnetic field unit and the first outer magnetic field unit together form a first electromechanical converter. The first crank arm has a first securing surface on a face which points radially outwards with respect to a crankshaft axis and which is opposite a first connecting rod bearing. A first counterweight is fixed to the first securing surface in a formfitting manner in the radial direction, said first counterweight including a non-magnetizable material. The first magnetic field unit is arranged on a counterweight face pointing radially outwards with respect to the crankshaft axis.

This application is a 371 National Phase of PCT Application No.PCT/EP2014/078926, filed on Dec. 19, 2014; and this application claimspriority of Application No. EP 13199214.1 filed in Europe on Dec. 20,2013, and which is herein incorporated by reference in its entirety.

The present invention relates to a reciprocating-piston engine having anelectromechanical converter which can be operated as an electricalgenerator and/or as an electric motor, according to the preamble ofindependent claim 1.

EP 1 223 316 B1 discloses a reciprocating-piston engine, in the crankchamber of which there is arranged an electromechanical converter whichhas the function of an electric motor and/or of an electrical generator.Magnetic-field-generating elements in the form of permanent magnets arearranged on a crankshaft, which is held rotatably in the crank chamberby way of a bearing cover attached to a cylinder block. The permanentmagnets are inserted fixedly, by way of an interference fit, in recessesof the balancing weights of the crankshaft, and serve as additionalbalancing weights. Coils are held in static fashion in the crank chamberon the bearing cover. During rotation of the crankshaft, the permanentmagnets rotate relative to the static coils, whereby a voltage isinduced in the coils owing to the electromagnetic interaction betweenthe permanent magnets and the coils, and the electromechanical converteracts as a generator. By feeding an alternating voltage to the coils, inparticular from a battery, an electromagnetic force is exerted on thepermanent magnets, and by way of the electromagnetic interaction, theelectromechanical converter acts as an electric motor. Since the coilsare held on the bearing cover, the coils can, together with the bearingcover, be attached to and removed from the cylinder block, which permitssimple assembly and disassembly or exchange of the coils. It is alsodescribed that, for improved cooling, the coils are arranged in theregion of the oil pan of the crank chamber and dip into the oilcontained in the oil pan, whereby cooling of the coils by way of the oilis made possible.

In the case of the reciprocating-piston engine known from the prior art,the magnetic-field-generating elements in the form of permanent magnetsare arranged in the balancing weights of the crankshaft by being fixedin recesses of the balancing weights by way of an interference fit. Thearrangement of the permanent magnets in the provided recesses of thebalancing weights has the advantage that the permanent magnets serve asadditional balancing weights, and therefore an additional increase inweight of the crankshaft owing to the permanent magnets, in relation toa conventional crankshaft, can be avoided. Said arrangement however alsohas several disadvantages. Crankshafts are generally of unipartite formand are manufactured either in a casting process, in particular fromspheroidal graphite iron, tempering steel or nitriding steel, or in apressure forming process. The materials suitable for the production ofhighly loadable crankshafts are generally magnetizable. In other words,conventional crankshafts have ferromagnetic or ferrimagneticcharacteristics. They are thus attracted by the magnetic pole of anexternal magnetic field without a high level of residual magnetizationremaining; in other words, they are magnetically soft, or themselvesgive rise, after magnetization, to a static magnetic field because theyare magnetically hard and exhibit high remanence. Because of thesemagnetizable characteristics, conventional crankshafts exhibit onlylimited suitability for the arrangement of permanent magnets in recessesof balancing weights by way of an interference fit, because thepermanent magnets give rise to magnetization of the crankshaft as awhole, and the generation of a directed magnetic field, which runs in adefined manner, for the efficient induction of a voltage in the coilssurrounding the crankshaft is not possible. Furthermore, there is therisk of demagnetization of the permanent magnets. The arrangementdescribed in EP 1 223 316 B1 thus requires either the use of acrankshaft composed of a non-magnetizable material or systemicallyexhibits low electrical power owing to the arrangement of the permanentmagnets. Since a crankshaft balancing weight, in order to perform itsgeneric function, extends only in a range situated opposite the adjacentconnecting-rod bearing, said range generally being considerably lessthan 120° and thus encompassing less than one third of the rotationalcircumference, the permanent magnets in the balancing weight can alsoonly be arranged in said partial range, whereby the maximum electricalpower of the electromechanical converter is severely limited.Furthermore, the arrangement of the permanent magnets by way of aninterference fit in the crankshaft is cumbersome from a productionaspect, and there is the risk of the permanent magnets becoming detachedat high crankshaft rotational speeds.

The problem on which the present invention is based consists inrealizing a reciprocating-piston engine with integratedelectromechanical converter, which reciprocating-piston engine isdistinguished by increased electrical power, a simple construction andsimplified serviceability, and which can be based on a conventional,non-electrified and only slightly modified reciprocating-piston engine.

Said object is achieved by way of the realization of the features of theindependent claims. Features which refine the invention in analternative or advantageous manner emerge from the dependent patentclaims.

The reciprocating-piston engine according to the invention, which can beused in particular as a motor vehicle engine, marine engine or staticengine, comprises a cylinder block with a crank chamber which is formedat least partially in the cylinder block. The crank chamber ispreferably closed off at the top by a corresponding structure of thecylinder block and at the bottom by an oil pan.

Within said crank chamber there is arranged a crankshaft. The crankshaftis rotatable, in multiple main bearings, about a crankshaft axis, thatis to say is mounted so as to be rotatable about the crankshaft axis. Inparticular, the crankshaft is held in the crank chamber, so as to berotatable about the crankshaft axis, by bearing covers which arefastened to the cylinder block preferably by way of screws. Thecrankshaft, which is preferably of unipartite form, but which may alsobe assembled from multiple parts, is composed of a magnetizablematerial. This is to be understood to mean that the crankshaft hasferromagnetic or ferrimagnetic characteristics at least in the region ofits crank webs, and is magnetizable there. The crankshaft is thusattracted by the magnetic pole of an external magnetic field without ahigh level of residual magnetization remaining; in other words, saidcrankshaft is magnetically soft, or itself gives rise, aftermagnetization, to a static magnetic field because it is magneticallyhard owing to a high remanence. In particular, the crankshaft is eithermanufactured in a casting process, for example from spheroidal graphiteiron, tempering steel or nitriding steel, or is forged in a pressureforming process.

The crankshaft comprises, between two main bearings in which it ismounted so as to be rotatable about the crankshaft axis, at least oneconnecting-rod bearing which is offset with respect to the crankshaftaxis. The offset is formed in each case by a crank web, which extends atleast partially in a radial direction in relation to the crankshaftaxis, between a main bearing and a connecting-rod bearing. In otherwords, the crank web extends with a geometrical direction component in adirection perpendicular to the crankshaft axis, that is to say in aradial direction. In relation to the crankshaft axis, the crank web isarranged axially adjacent to the first connecting-rod bearing. “Axiallyadjacent” is to be understood to mean that the crank web is situateddirectly or indirectly adjacent to the connecting-rod bearing in adirection running parallel to the crankshaft axis.

At least one first connecting rod, on which a linearly guided firstpiston is arranged, is mounted rotatably in a first connecting-rodbearing of the crankshaft. During rotation of the crankshaft, theconnecting rod performs a connecting-rod movement in a geometricconnecting-rod movement space. The connecting-rod movement is to beunderstood to mean the geometric movement space passed through by theconnecting rod, which is made up of the lower connecting-rod eye mountedin the connecting-rod bearing, of the connecting-rod bearing cover, ofthe connecting-rod shank and of the connecting-rod head, during one fullrotation of the crankshaft and one complete reciprocating movement ofthe piston. In other words, the connecting-rod movement space is thatgeometric free space within the crank chamber which is required for theunhindered movement of the connecting rod. It is possible for multipleconnecting rods to be arranged adjacent to one another on the sameconnecting-rod bearing. In this case, the connecting-rod movement spaceis that free space within the crank chamber which is required for thefree mobility of both connecting rods.

The first crank web, in particular all of the crank webs of thecrankshaft, has/have a first fastening surface on a side which pointsradially outward with respect to the crankshaft axis and which issituated opposite the first connecting-rod bearing. In other words, thefastening surface points, at least with one direction component, in adirection which extends perpendicular to the crankshaft axis—that is tosay radially—and which, in relation to the crankshaft axis, pointstoward the side situated opposite the side of which the connecting-rodbearing is located.

A fastening surface is to be understood generally to mean a mechanicalinterface which permits positively locking arrangement of a component,wherein the positive locking is realized in a radial direction, that isto say perpendicular to the crankshaft axis.

A first balancing weight is fixed in positively locking fashion in aradial direction, and in particular also in a circumferential direction,to the first fastening surface. Positive locking in a radial directionor circumferential direction is to be understood to mean a connectionwith an undercut such that positively locking fixing is realized atleast in a radial direction or in a circumferential direction,respectively, with respect to the crankshaft axis. In other words, thefirst balancing weight is fixed in positively locking fashion to thefastening surface such that the balancing weight remains fixed on thecrankshaft during rotation of said crankshaft. In particular, thepositive locking is realized by way of a screw connection.

In particular, the first fastening surface and/or the first balancingweight have/has at least one threaded bore, wherein the positivelylocking connection is produced by way of at least one screw guidedthrough a passage bore which is formed in the first balancing weight andin the first fastening surface.

Alternatively or in addition, the positively locking connection may berealized by way of an undercut which extends in particular parallel tothe crankshaft axis and which is formed for example by a linear guide,which runs axially or extends parallel to the crankshaft, between thefirst fastening surface and the first balancing weight, in particular adovetail-like guide, wherein the first balancing weight is held in adirection parallel to the crankshaft axis, that is to say axially, forexample in non-positively locking, frictionally engaging or positivelylocking fashion, in particular by way of a screw connection.

The first balancing weight is composed of a non-magnetizable material.In particular, the first balancing weight is composed of cast iron,high-grade steel, carbon fiber, a ceramic material, aluminum and/or atleast one other non-magnetizable material. Cast-iron is formed inparticular by austenitic cast-iron, in particular gray cast iron. Carbonfiber is in particular sintered. Alternatively, it is however alsopossible for the first balancing weight to be made up of a combinationof at least two of said materials, or of one of said materials with afurther non-magnetizable material. In particular, the balancing weightmay also be composed of an encapsulated non-magnetizable material. Saidmaterial preferably has a high specific weight. The weight and thearrangement of the balancing weight, together with the weight of thefirst inner magnetic field unit described further below and arranged onthe balancing weight, should be such that the rotating inertia forceresulting from the eccentricity of the first connecting-rod bearing, ofthe at least one first connecting rod and in particular of the firstpiston is substantially, preferably entirely, compensated. Therespective proportion of balancing weight and inner magnetic field unitmay vary as desired, as long as the mass balancing is substantially orfully possible.

The first inner magnetic field unit is arranged on a side, which pointsradially outward in relation to the crankshaft axis, of the firstbalancing weight. In other words, the first inner magnetic field unitand the first balancing weight are connected to one another, wherein thefirst inner magnetic field unit extends in a direction radially outwardin relation to the crankshaft axis. In particular, the first innermagnetic field unit is pushed into a first linear guide, which extendsin an axial direction—that is to say substantially parallel to thecrankshaft axis—on the first balancing weight and is fixed axiallythere, such that said first inner magnetic field unit is also fixedlyheld, for example with non-positively locking, frictionally engaging orpositively locking action, in a direction parallel to the crankshaftaxis during normal operation of the crankshaft. Said first linear guidefixes the first inner magnetic field unit in positively locking fashionin a radial direction and circumferential direction in relation to thecrankshaft axis. Positive locking in a radial direction andcircumferential direction is generally to be understood to mean aconnection with an undercut such that positively locking fixing isrealized at least in a radial direction or in a circumferentialdirection, respectively, with respect to the crankshaft axis. In otherwords, the first inner magnetic field unit is fixed in positivelylocking fashion to the first balancing weight of the fastening surfacesuch that the first inner magnetic field unit remains fixed on thecrankshaft during rotation of said crankshaft.

Thus, the first inner magnetic field unit is, by way of the firstbalancing weight fixed to the first fastening surface, arranged on thefirst crank web of the crankshaft such that the first inner magneticfield unit points radially outward in relation to the crankshaft axis.Here, during rotation of the crankshaft, the first inner magnetic fieldunit circulates around the crankshaft axis on a geometric first circularpath which is axially adjacent to the connecting-rod movement space. Inother words, both the first inner magnetic field unit and the firstbalancing weight are shaped and arranged such that the connecting rod,on the one hand, and the first inner magnetic field unit and the firstbalancing weight, on the other hand, move without colliding duringrotation of the crankshaft, wherein the movement spaces of theconnecting rod, on the one hand, and of the first inner magnetic fieldunit and of the first balancing weight, on the other hand, are situatedin axially spaced-apart but axially mutually adjacent opposed positions.

In the case of a conventional, non-electrified reciprocating-pistonengine with a conventional crankshaft with integrally formed balancingweights, said collision-free mobility within the crank chamber isalready realized. Thus, it is possible for the balancing weights of aconventional crankshaft of said type to be removed in particular by wayof a cutting machining process, and for a fastening surface for thenon-magnetizable balancing weight to be provided, wherein thenon-magnetizable balancing weight and the inner magnetic field uniteither have substantially the same cross section in the radial and axialdirections—that is to say the same rotational cross section—as theremoved balancing weight, or have an enlarged rotational cross sectionin order to utilize the available space in the crank chamber to bestpossible effect. The extent in a circumferential direction, that is tosay along the circular movement path of the non-magnetizable balancingweight and of the inner magnetic field unit, may be varied as desired ingeometric terms, because said space within the crank chamber remainsfree in order to permit the free rotatability. To permit compensation ofthe rotating inertia force, it is however advantageous for the extent ofthe non-magnetizable balancing weight in the circumferential directionto be limited substantially to the range situated opposite theconnecting-rod bearing.

In one variant of the invention, the non-magnetizable balancing weightand the inner magnetic field unit are of unipartite form and are inparticular accommodated in the same housing, wherein the unipartite unitcan be divided functionally into a balancing weight section and asection of the inner magnetic field unit.

The first fastening surface and further sections of the crankshaft mayserve, in addition to the at least one non-magnetizable balancingweight, as balancing weights for the mass balancing. It is likewisepossible for the reciprocating-piston engine to additionally have abalancing shaft for the compensation of inertia forces and/or inertiatorques.

A first outer magnetic field unit is arranged in static fashion in thecrank chamber so as to be radially spaced apart from the first circularpath of the first inner magnetic field unit. In other words, said firstouter magnetic field unit surrounds, engages around or encloses thefirst circular path of the first inner magnetic field unit. In otherwords again, said first outer magnetic field unit is arranged radiallyoutside the rotational movement space of the first inner magnetic fieldunit, and engages either partially or fully around said movement space,in particular with an engaging-around angle of between 120° and 360°.

The first inner magnetic field unit and the first outer magnetic fieldunit are arranged and designed such that, together, they form a firstelectromechanical converter, in particular an electric motor or anelectrical generator. For this purpose, one of the two magnetic fieldunits forms a magnetic-field-generating unit, and the other forms a coilunit which, at least in a subsection of a full rotation of thecrankshaft, is acted on by the magnetic field of themagnetic-field-generating unit, wherein a voltage is induced in the coilunit by a magnetic field which changes owing to rotation of thecrankshaft, such that the electromechanical converter acts as agenerator, or wherein, by application of an electrical voltage to thecoil unit, a magnetic field can be generated, by way of which a forcecan be exerted on the magnetic-field-generating unit and thus on thecrankshaft, and the crankshaft can thus be set in rotation, such thatthe electromechanical converter acts as an electric motor.

In other words, during rotation of the crankshaft, themagnetic-field-generating unit and the coil unit rotate relative to oneanother, whereby, owing to the electromagnetic interaction between themagnetic-field-generating unit and the coil unit, a voltage is inducedin the coil unit, and the electromechanical converter acts as agenerator. By feeding an alternating voltage to the coil unit, inparticular from a battery, an electromagnetic force is exerted on themagnetic-field-generating unit, and by way of the electromagneticinteraction, the electromechanical converter acts as an electric motor.

The first inner magnetic field unit arranged on the crankshaft may beformed by a first inner permanent magnet unit, which generates apermanent magnetic field by way of at least one permanent magnet, or bya first inner coil unit, by means of which an electromagnetic field canbe generated, or in which a voltage can be induced by way of a magneticalternating field.

The first outer magnetic field unit arranged in static fashion in thecrank chamber may also be formed by a first outer coil unit, by way ofwhich an electromagnetic field can be generated or in which a voltagecan be induced by way of a magnetic alternating field, or by a firstouter permanent magnet unit, which generates a permanent magnetic fieldby way of at least one permanent magnet. In order that the two magneticfield units can form an electromagnetic converter, at least one of thetwo magnetic field units must be in the form of a coil unit.

An advantage of the reciprocating-piston engine according to theinvention consists in that, owing to the arrangement of anon-magnetizable balancing weight on the magnetizable crankshaft and thearrangement of the first inner magnetic field unit on saidnon-magnetizable balancing weight, magnetization of the crankshaft, andthus adverse influencing of the magnetic field by the crankshaft, can besubstantially prevented, because the non-magnetizable balancing weightacts as a magnetic insulator between the crankshaft and the innermagnetic field unit. Thus, long-term demagnetization of the permanentmagnets is also reduced, if the first inner magnetic field unit is inthe form of a permanent magnet unit.

A further advantage consists in that the extent of the first innermagnetic field unit in a circumferential direction, that is to say alongthe circular movement path of the inner magnetic field unit, can besubstantially independent of the extent of the first balancing weight,because the latter, owing to the generic function of a balancing weight,is restricted to the range situated opposite the connecting-rod bearing.For example, it is possible for the extent of the balancing weight in acircumferential direction to amount to less than 135°, in particularless than 120°, especially less than 90°, whereas the extent of theinner magnetic field unit in the circumferential direction amounts togreater than 135°, in particular greater than 180°, in particulargreater than 210°, especially greater than 360°, wherein, in the case ofan extent of 360°, the inner magnetic field unit has the geometricoutline of a closed ring. This has the effect that the entirecircumference of the first geometric circular path is utilized for thearrangement of the inner magnetic field unit, and thus the achievableelectrical power of the first electromechanical converter can beconsiderably increased.

In a refinement of the invention, the first inner magnetic field unithas the shape of a circular-arc-shaped inner ring section whichsurrounds the first crank web and which has a geometric first axis whichlies on the crankshaft axis. In other words, the first inner magneticfield unit has the shape of a ring section, that is to say of a ringsegment, which has a circular arc shape, wherein the axis about whichthe circular arc or the ring segment extends and on which the centralpoint of the circular arc lies is formed by a geometric first axis. Inthe assembled state of the crankshaft and first inner magnetic fieldunit, the first axis and the crankshaft axis coincide and form a commonaxis. In other words again, the circular-arc-shaped first inner magneticfield unit extends in a circumferential direction in relation to thecrankshaft axis, that is to say along the circular movement path of theinner magnetic field unit, with the first axis as geometric centralaxis. In particular, the circular-arc-shaped inner ring section extendswith a first center angle of greater than 135°, in particular greaterthan 180°, in particular greater than 210°. The center angle is to beunderstood to mean the angle, also referred to as central angle,enclosed, at the central point of the geometric circular arc, by the twocircle radii which delimit the geometric circular arc.

In a particular refinement, the circular-arc-shaped inner ring sectionextends with a first center angle of 360°, wherein the first innermagnetic field unit has the shape of a closed circular inner ringsurrounding the first crank web. In other words, the first innermagnetic field unit has the shape of a closed ring, in other words of ageometric circle, wherein said inner ring at least partially or fullysurrounds the first crank web of the crankshaft. The geometric centralpoint of said ring lies on the first axis or on the crankshaft axis.

In a refinement of the invention, the first outer magnetic field unitmay also have the shape of a circular-arc-shaped outer ring section witha geometric second axis which lies on the crankshaft axis. Saidcircular-arc-shaped outer ring section surrounds the first circular pathof the first inner magnetic field unit with a radial spacing. Inparticular, the inner and outer ring sections run concentrically. If thefirst inner magnetic field unit has the shape of a circular-arc-shapedinner ring section or of a ring, the outer diameter of said inner ringsection or ring is in particular smaller than the inner diameter of theouter ring section or ring. In particular, the circular-arc-shaped outerring section extends with a second center angle of greater than 135°, inparticular greater than 180°, in particular greater than 210°. In aparticular embodiment of the invention, the circular-arc-shaped outerring section extends with a second center angle of 360°, wherein thefirst outer magnetic field unit has the shape of a closed circular outerring which surrounds the first circular path of the first inner magneticfield unit with a radial spacing.

The described ring sections or rings may have any desired cross section,in particular a rectangular, square, polygonal, circular, oval or othercross section.

The outer magnetic field unit is in particular arranged on a bearingcover of a main bearing, which is adjacent to the first crank web, ofthe crankshaft. For this purpose, the outer magnetic field unit may havea bracket which are fixed to the bearing cover by way of bearing coverscrews which also connect the bearing cover to the cylinder block. Thus,the outer magnetic field unit can be arranged in a conventionalreciprocating-piston engine without the provision of further fasteningelements.

In a preferred embodiment, the first inner magnetic field unit ispermanently magnetic and is in the form of a first inner permanentmagnet unit. This has the advantage that no electrical connection ormeans for voltage transmission to the rotatable crankshaft has to beproduced.

The first inner permanent magnet unit has at least one permanent magnetwhich is designed and arranged such that, during rotation of thecrankshaft, a magnetic alternating field, that is to say a changingmagnetic field, exists in a region situated radially outside the firstinner permanent magnet unit, which region does not co-rotate. In otherwords, the first inner permanent magnet unit is designed such that,during rotation thereof, a magnetic alternating field prevails in thefirst outer magnetic field unit, and a voltage can be induced there.

In a refinement of the invention, the first inner permanent magnet unithas first permanent magnets arranged in a line with one another in acircle-circumferential direction in relation to the crankshaft axis, insuch a way that the magnetic polarity of the first permanent magnetsalternates in the circle-circumferential direction such that a magneticalternating field is generated during rotation of the crankshaft. Inother words, north and south poles of multiple permanent magnets of thepermanent magnet unit alternate such that a changing magnetic field isgenerated during rotation of the crankshaft. In particular, the firstpermanent magnets are arranged adjacent to one another, in particularalong the circular-arc-shaped inner ring section, and have north polespointing in a common circumferential direction. The magnetic axisrunning between the north and south pole of each permanent magnet thusruns in the circle-circumferential direction with respect to the rotarypath. Said magnetic axis thus forms in particular a tangent to thecircular path of the first inner permanent magnet unit, or runs parallelto a tangent of said type, or runs as a circular arc parallel to saidcircular path. Alternatively, the first permanent magnets may have,adjacent to one another in particular along the circular-arc-shapedinner ring section, north and south poles of alternating polarityorientation pointing in a radial direction. In other words, the magnetaxes running between the north and south poles of each permanent magnetthus run in each case radially with respect to the first axis or withrespect to the crankshaft axis; in particular, said magnet axesintersect substantially at a point lying on the first axis or on thecrankshaft axis, wherein the polarity orientation of adjacent permanentmagnets alternates in each case.

Any other permanent magnet orientations which give rise to the describedmagnetic alternating field during rotation of the crankshaft arepossible according to the invention.

The first inner magnetic field unit may however alternatively beelectromagnetic, in the form of a first inner coil unit. In particular,the permanent magnets are replaced by coils. In this case, the magneticfield is generated by the first inner magnetic field unit not bypermanent magnets but rather electromagnetically, or a magnetic fieldgenerated by the first outer magnetic field unit electromagneticallyinteracts with the first inner coil unit, and induces a voltage there.

Possible refinements of the invention provide different coilarrangements of the first inner coil unit. The coil arrangementscorrespond, in part, to the arrangements of the permanent magnetsalready described above, wherein the above statements relating to thepermanent magnets also apply to the coils.

In a first variant, the first inner coil unit has first coils which arearranged in a line with one another in a circle-circumferentialdirection in relation to the crankshaft axis, the first coil axes ofwhich first coils run radially in relation to the crankshaft axis. Inparticular, said coil axes intersect substantially at a point close toor on the first axis or the crankshaft axis. In particular, the firstcoils are arranged and/or interconnected such that the magnetic polarityof the first coils alternates in the circle-circumferential direction,such that a magnetic alternating field is generated during rotation ofthe crankshaft. This may be realized for example in that the firstcoils, arranged in a line with one another, are supplied with voltage ofalternating electrical polarity, or in that the coil windings arealternately inverse, such that the magnetic polarity of the first coilsalternates in the circle-circumferential direction, such that a magneticalternating field is generated during rotation of the crankshaft. Inother words, north and south poles of multiple first coils of the firstcoil unit alternate such that a changing magnetic field is generatedduring rotation of the crankshaft. It is firstly possible for themagnetic field generated by way of the first coil unit to be constantrelative to the first coil unit by virtue of a constant voltage supplybeing provided to the first coils, or for the magnetic field generatedby way of the first coil unit to also alternate relative to the firstcoil unit by virtue of the voltage supply of the first coilsalternating. Said alternation may be realized in particular by way of acommutator.

In a second variant, the first inner coil unit comprises at least onefirst coil which extends in the circle-circumferential direction and thefirst coil axis of which runs in the circle-circumferential direction.In the third variant, the first inner coil unit has at least one firstcoil, the first coil axis of which runs parallel to the crankshaft axis.

To generate a magnetic field by way of the at least one first coil, inparticular the first coils, said first coil or coils may either besupplied with a voltage, or the first coils are interconnected with oneanother, and arranged, such that, during rotation of the crankshaft andunder the action of an external magnetic field, which is effected inparticular by the first outer magnetic field unit and which inparticular alternates owing to the rotation, on the first coils, saidfirst coils supply voltage to one another, in particular by beingdesigned as a short-circuit rotor, for example of an asynchronousmachine.

To supply voltage to the first inner coil unit, the crankshaft may forexample have sliding contacts in the crank chamber between the cylinderblock and the crankshaft, by way of which sliding contacts a multipolarelectrical connection to the coil unit can be produced. In particular,said connection is a two-pole, three-pole or multipolar connection inorder to supply several of the first coils with different voltages inalternating fashion. This alternating voltage supply may be realized ina manner dependent on the position of the crankshaft. For this purpose,the sliding contacts may also be in the form of a commutator. Asliding-contact connection of said type is substantially non-critical inthe case of an engine whose crank chamber contains engine oil, but isassociated with risks especially in the case of an internal combustionengine operated with a fuel-oil mixture, in particular a two-strokeengine, owing to possible spark generation. Furthermore, slidingcontacts are subject to increased wear.

Therefore, in one refinement, the invention also comprises a contactlessvoltage supply to the at least one first coils of the first inner coilunit on the crankshaft. For this purpose, the first inner coil unit hasat least one additional coil which is electrically connected to the atleast one first coil. A permanently magnetic or electromagnetic lateralmagnetic field unit is arranged in static fashion in the crank chamberaxially adjacent to the first circular path of the first inner coilunit. The at least one additional coil and the lateral magnetic fieldunit are arranged relative to one another, in particular are in axiallyopposed positions with respect to one another in relation to thecrankshaft axis, and designed, such that, during rotation of thecrankshaft about the crankshaft axis, said at least one additional coiland lateral magnetic field unit together form an electrical generatorfor the supply of electrical voltage to the at least one first coil. Theat least one additional coil has, in particular, an additional-coil axisrunning parallel to the crankshaft axis. In particular, the at least oneadditional coil is formed by multiple additional coils arranged in aline with one another in a circle-circumferential direction. Saidadditional coils arranged in a line with one another haveadditional-coil axes running preferably parallel to the crankshaft axis.In particular, each first coil is assigned a first additional coil,wherein the first coil and the first additional coil are electricallyconnected. The first additional coils are preferably integrated in thefirst coil unit. The lateral magnetic field unit is in particularelectromagnetic, and is formed by multiple lateral coils arranged in aline with one another in a circle-circumferential direction, inparticular with lateral-coil axes running parallel to the crankshaftaxis. By application of an electric alternating voltage to the lateralcoils, and/or during rotation of the crankshaft, magnetic induction inthe additional coils occurs owing to the magnetic interaction betweenthe lateral coils and the additional coils. With the voltage therebygenerated, the first coils of the first inner coil unit are suppliedwith voltage, such that said first coils in turn generate anelectromagnetic field, by way of which, during rotation of thecrankshaft, a voltage can be induced in the outer magnetic field unit.

An advantage of said arrangement consists in that the use of permanentmagnets can be either entirely or partially dispensed with, and thereciprocating-piston engine, during combustion engine operation, can,with the first inner coil unit in a voltage-free state, be operatedwithout magnetic resistance, whereby the efficiency of the combustionengine is increased.

In one variant of the invention, the first outer magnetic field unit iselectromagnetic and is in the form of a first outer coil unit, whereinthe first inner magnetic field unit is either permanently magnetic orelectromagnetic. The first outer coil unit may have second coilsarranged in a line with one another in a circle-circumferentialdirection, the second coil axes of which second coils run radially inrelation to the crankshaft axis. In particular, the second coil axes ofthe preferably uniformly distributed second coils intersectsubstantially at a point which lies close to or on the second axis orthe crankshaft axis. In other words, the second coils arearranged—preferably uniformly—in stellate fashion on the first outermagnetic field unit.

Alternatively, the first outer coil unit comprises at least one secondcoil which extends in a circle-circumferential direction and the secondcoil axis of which runs in the circle-circumferential direction. Thesecond coil axis may for example run either in circular-arc-shapedfashion or in straight fashion, wherein, in the former case, thecircular arc preferably runs concentrically with respect to thecircular-arc-shaped outer ring section or the circular path of the firstinner magnetic field unit, with a geometric axis lying on the secondaxis. In the latter case, that is to say a straight second coil axis,said second coil axis preferably runs parallel to a tangent to thecircular-arc-shaped outer ring section.

In a further variant, the first outer coil unit comprises at least onesecond coil, the second coil axis of which runs parallel to thecrankshaft axis. On the one hand, said at least one second coil mayfully surround the crankshaft, wherein the first outer coil unit has theshape of a closed circular outer ring which surrounds the first circularpath of the first inner magnetic field unit with a radial spacing. Inthis case, the second coil axis, which runs parallel to the crankshaftaxis, lies preferably on said crankshaft axis. Alternatively, the atleast one second coil is arranged adjacent to the first inner magneticfield unit and has, in particular, a circular arc shape or banana shape.

If the first inner magnetic field unit is electromagnetic, the firstouter magnetic field unit may, instead of an electromagnetic design, bepermanently magnetic, wherein the first outer magnetic field unit isformed by a first outer permanent magnet unit. In this case, the firstouter permanent magnet unit has second permanent magnets arranged in aline with one another in relation to the crankshaft axis in thecircle-circumferential direction, in particular in such a way that themagnetic polarity of the second permanent magnets alternates in thecircle-circumferential direction, such that a magnetic alternating fieldis generated during rotation of the crankshaft. The second permanentmagnets are arranged adjacent to one another along thecircular-arc-shaped inner ring section, and have north poles pointing ina common circumferential direction. Alternatively, the second permanentmagnets are arranged adjacent to one another along thecircular-arc-shaped inner ring section, and have poles of alternatingpolarity orientation pointing in a radial direction. Any other type ofarrangement or orientation of the second permanent magnets in the firstouter permanent magnet unit is possible as long as, during rotation ofthe first inner coil unit, said coil unit is acted on by a relativealternating field of said type such that the two units together form anelectromechanical converter.

Up to this point, the invention has been described on the basis of acrankshaft having a single first connecting-rod bearing, a single firstconnecting rod which is mounted rotatably in the first connecting-rodbearing of the crankshaft, and a single first crank web, which isaxially adjacent to the first connecting-rod bearing in relation to thecrankshaft axis, wherein the first inner magnetic field unit arrangedaccording to the invention on the first crank web, and the first outermagnetic field unit, together form a first electromechanical converter.

The reciprocating-piston engine however preferably additionally has asecond electromechanical converter arranged on the second crank web,which is situated axially opposite the first crank web, of the firstconnecting-rod bearing, wherein said second electromechanical converterhas in particular the same features as the first electromechanicalconverter or has corresponding variations according to the invention ofsaid first electromechanical converter. The second crank web may alsohave a second fastening surface corresponding to the first crank web, onwhich second fastening surface there is arranged a second balancingweight which corresponds to the first balancing weight.

In particular, the reciprocating-piston engine comprises a second innermagnetic field unit, said second inner magnetic field unit beingarranged on a second crank web, which is axially adjacent to the firstconnecting-rod bearing and which is situated axially opposite the firstcrank web, of the crankshaft in such a way that the second innermagnetic field unit points radially outward in relation to thecrankshaft axis and, during rotation of the crankshaft, circulatesaround the crankshaft axis on a geometric second circular path which isaxially adjacent to the connecting-rod movement space. A second outermagnetic field unit is arranged in static fashion in the crank chamberso as to be radially spaced apart from the second circular path, in sucha way that the second outer magnetic field unit and the second innermagnetic field unit together form a second electromechanical converter.The connecting-rod movement space of the at least one first connectingrod extends in an axial intermediate space between the first circularpath and the second circular path. The second crank web has a secondfastening surface on a side which points radially outward in relation tothe crankshaft axis and which is situated opposite the firstconnecting-rod bearing. A second balancing weight is fixed in positivelylocking fashion in a radial direction to the second fastening surface.The second balancing weight is composed of a non-magnetizable material.The second inner magnetic field unit is arranged on a radially outwardlypointing side of the second balancing weight. In particular, the secondinner magnetic field unit corresponds to the first inner magnetic fieldunit. In particular, the second outer magnetic field unit corresponds tothe first outer magnetic field unit. In particular, the second balancingweight corresponds to the first balancing weight.

It is also possible for two first connecting rods to be arranged on thefirst connecting-rod bearing, which first connecting rods are mounted,adjacent to one another, rotatably in the first connecting-rod bearingof the crankshaft, and which first connecting rods, during rotation ofthe crankshaft, jointly perform a connecting-rod movement in twodifferent connecting-rod movement spaces which form the commongeometrical connecting-rod movement space, as is the case in particularin V-configuration engines.

The described arrangement having one or two electromechanical convertersper connecting-rod bearing, and one or two connecting rods perconnecting-rod bearing, may be used, according to the invention, in anymulti-cylinder engine of in-line configuration, V-configuration,VR-configuration, W-configuration or other type of construction, whereinthe one or more electromechanical converters are arranged, according tothe invention, either only on some of the connecting-rod bearings or onall connecting-rod bearings. In particular, said multiplicity ofelectromechanical converters is individually switchable in a mannerdependent on the power demand.

A particular advantage of the invention consists in that the describedelectrified reciprocating-piston engine can be based on a conventional,non-electrified reciprocating-piston combustion engine, that is to sayone which is not equipped with an integrated electric motor orgenerator, in particular an Otto-cycle or diesel combustion engine. Itis thus possible for a purely combustion-engine-driven vehicle to bedriven electrically, and/or equipped with an additional generator, usingthe same base combustion engine with relatively minor adaptations of thereciprocating-piston engine. For the integration of theelectromechanical converter, only relatively minor adaptations to thereciprocating-piston engine are required, primarily to the crankshaftthereof. The crankshaft according to the invention may be based on aconventional crankshaft, and may in particular be produced by way of acutting machining process.

A further advantage of the invention consists in that theelectromechanical converter can be integrated entirely in the crankcaseof the reciprocating-piston engine, such that additional electric motorsfor driving the vehicle, in particular the hybrid vehicle, or generatorsfor electricity generation can be omitted. Furthermore, an externalalternator can be dispensed with.

The reciprocating-piston engine may comprise an oil pan which closes offthe crank chamber, and the coil units may dip into the oil situated inthe oil pan, whereby cooling of the coil units by way of the oilcontained in the oil pan, and consequently cooling of theelectromechanical converter, is realized.

A further aspect of the invention provides that the crankshaft iscomposed of a magnetizable or non-magnetizable material, the first crankweb, on a side which points radially outward in relation to thecrankshaft axis and which is situated opposite the first connecting-rodbearing, does not have a first fastening surface but rather is formedintegrally with the first balancing weight, the first balancing weightis accordingly, like the crankshaft, composed of a magnetizable ornon-magnetizable material or, alternatively, the first crank web has thedescribed first fastening surface but the balancing weight is composedof a magnetizable material, and wherein the first inner magnetic fieldunit is arranged on a side, which points radially outward in relation tothe crankshaft axis, of the first balancing weight, wherein the firstinner magnetic field unit has the shape of a circular-arc-shaped innerring section which surrounds the first crank web and which has ageometric first axis which lies substantially on the crankshaft axis,and the circular-arc-shaped inner ring section extends with a firstcenter angle of greater than 135°, in particular greater than 180°, inparticular greater than 210°, wherein in particular, the first centerangle is greater, by at least 60°, in particular by at least 90°, inparticular by at least 120°, than the center angle of thecircumferential extent of the balancing weight, wherein in particular,the circular-arc-shaped inner ring section projects beyond the firstbalancing weight to one side or to both sides in a circumferentialdirection by at least 30°, in particular by at least 60°, in particularby at least 90°. In particular, the circular-arc-shaped inner ringsection extends with a first center angle of 360°, and the first innermagnetic field unit has the shape of a closed circular inner ring whichsurrounds the first crank web. The other features of thereciprocating-piston engine may be as described in the introduction.

The invention also comprises a system composed of the describedreciprocating-piston engine according to the invention, of a chargeableand dischargeable electrical energy store, of an electrical controlunit, and of a crankshaft sensor for detecting a position of thecrankshaft. The energy store may for example be a chargeable anddischargeable battery or a capacitor. The electrical control unit may beformed in particular by an electronic controller, in particular anengine control unit. The crankshaft sensor is for example an electronicangle sensor, by way of which the angular position—in particulardiscrete angle position ranges —of the crankshaft relative to thecylinder block can be detected and supplied, in particular by way of anelectrical signal, to the control unit.

The control unit of the system is electrically interconnected with theelectrical energy store, with the first electromechanical converter and,if provided, with the second or each further electromechanicalconverter, and designed, in particular programmed, such that thereciprocating-piston engine can be switched between an electric-motoroperating mode and a generator operating mode.

In the electric-motor operating mode, the crankshaft can be driven withelectric motor action, by virtue of the electrical energy store beingdischarged, by application of a voltage to the at least oneelectromechanical converter, more specifically to the at least one coilunit thereof, such that the converter acts as an electric motor. In thegenerator operating mode, the electrical energy store can be charged byvirtue of the crankshaft being mechanically driven, in particular byvirtue of the crankshaft being driven with combustion engine action byway of the reciprocating-piston engine or by virtue of the crankshaftbeing driven by external action, for example by way of the vehiclewheels during the deceleration of the vehicle. The switching may beperformed automatically in a manner dependent on the operating mode ofthe reciprocating-piston engine, on the combustion engine power thereof,on the state of charge of the electrical energy store and/or on anexternal user preset. Such automatic switching systems are known inparticular from the field of hybrid vehicle technology.

The reciprocating-piston engine has an electrically actuable variableoutlet valve drive for at least one first outlet valve which is assignedto a first combustion chamber of a first piston which is coupled to theat least one first connecting rod, said electrically actuable variableoutlet valve drive being designed such that the at least one firstoutlet valve can be opened regardless of the position of the crankshaft.Such variable and freely actuable valve drives, in particularelectromechanical, electromagnetic or pneumatic valve drives, for theopening and closing of the inlet and/or outlet valves of areciprocating-piston engine are known in a variety of embodiments fromthe prior art.

According to the invention, the control unit is interconnected with thecrankshaft sensor and with the variable outlet valve drive, anddesigned, in particular programmed, such that, in the electric-motoroperating mode, the at least one first outlet valve is opened in aposition range of the crankshaft in which the first piston is situatedin a compression stroke. In particular, the first outlet valve is openduring the entire compression stroke and exhaust stroke of the piston,alternatively during a major part of the respective stroke, inparticular at least 35%, 50%, 75% or 90% of the stroke as measured inrelation to the reciprocating movement of the piston, such that thereciprocating-piston engine can be driven with electric motor actionwith reduced resistance. In particular, the control unit is programmedsuch that the outlet valve is open or opened in an angle position rangeof the crankshaft which corresponds to the compression stroke andexhaust stroke. This aspect of the invention can, according to theinvention, be implemented not only with the reciprocating-piston enginedescribed according to the invention, but generally in combination witha reciprocating-piston engine which has any crankshaft which ismechanically coupled to any electromechanical converter, in particularan electric motor or an electrical generator, wherein the crankshaft canbe driven by the electromechanical converter in an electric-motoroperating mode.

Furthermore, the invention comprises a further system which may be basedon, and have the features of, the system described in the introductionbut which does not necessarily have to be based thereon, and which mayalso be used as an independent system. Said further system comprises areciprocating-piston engine, which is in particular designed as one ofthe described reciprocating-piston engines according to the invention, achargeable and dischargeable electrical energy store, and a crankshaftsensor for detecting a position of the crankshaft, as already describedin conjunction with the above system. Additionally, the system comprisesan electric power control element. The latter is formed for example byan electrical control unit, in particular the electrical control unitmentioned in the introduction, or by an electronic controller, inparticular an engine control unit.

The reciprocating-piston engine has a first piston to which the firstelectromechanical converter, which is arranged on one side of the firstconnecting-rod bearing, and in particular the second electromechanicalconverter, which is arranged on the other side of the firstconnecting-rod bearing, are assigned. The first piston is coupled to theat least one first connecting rod, which is mounted rotatably in thefirst connecting-rod bearing of the crankshaft. Furthermore, thereciprocating-piston engine has a second piston to which a thirdelectromechanical converter, which is arranged on one side of a secondconnecting-rod bearing, and in particular a fourth electromechanicalconverter, which is arranged on the other side of the secondconnecting-rod bearing, are assigned. The second piston is coupled to atleast one second connecting rod, which is mounted rotatably in thesecond connecting-rod bearing of the crankshaft. In particular, thethird electromechanical converter corresponds to the firstelectromechanical converter, and the fourth electromechanical convertercorresponds to the second electromechanical converter.

The power control element is electrically interconnected with theelectrical energy store, with the first electromechanical converter andwith the third electromechanical converter, in particular also with thesecond electromechanical converter and/or with the fourthelectromechanical converter, in particular by way of an electronicsignal connection, and designed, in particular programmed, in such a waythat the reciprocating-piston engine can be operated in anelectric-motor operating mode. Alternatively, the power control elementis designed and interconnected such that the reciprocating-piston enginecan be operated in a generator operating mode. Alternatively, the powercontrol element is designed and interconnected such that thereciprocating-piston engine can be operated switchably either in anelectric-motor operating mode or in a generator operating mode. In theelectric-motor operating mode, the crankshaft can be driven withelectric motor action with adjustable power by virtue of the electricalenergy store being discharged, and by virtue of at least one of theelectromechanical converters being supplied with current from theelectrical energy store and being operated as an electric motor withadjustable mechanical output power. The adjustment of the power isperformed in particular in continuously variable fashion. In thegenerator operating mode, the electrical energy store can be chargedwith adjustable power by virtue of the crankshaft being mechanicallydriven, in particular by virtue of the crankshaft being driven withcombustion engine action by way of the reciprocating-piston engine or byvirtue of the crankshaft being driven by external action, for example byway of the vehicle wheels during the deceleration of the vehicle, and byvirtue of a current for charging the electrical energy store beingpicked off at least from one of the electromechanical converters andsaid at least one electromechanical converter being operated as agenerator with adjustable electrical power.

The power control element is electrically interconnected with theelectrical energy store, with the first electromechanical converter,with the third electromechanical converter and with the crankshaftsensor, in particular also with the second electromechanical converterand/or with the fourth electromechanical converter, and designed, inparticular programmed, such that the power can be distributed to thefirst electromechanical converter, in particular also to the secondelectromechanical converter, with a first power fraction, and to thethird electromechanical converter, in particular also to the fourthelectromechanical converter, with a second power fraction. Thus, thefirst power fraction is assigned to the first connecting-rod bearing andthe second power fraction is assigned to the second connecting-rodbearing. The weighting of the two power fractions, in other words thefraction of the variable power made up by the first power fraction andthat made up by the second power fraction, is thus likewise variable byway of the power control element.

The power control element is designed such that the distribution of thepower to the first electromechanical converter and to the thirdelectromechanical converter is performed in a manner dependent on theposition of the crankshaft. In other words, the power control element isdesigned such that the weighting of the two power fractions, that is tosay the fraction of the variable power made up by the first powerfraction and that made up by the second power fraction, is realized byway of the power control element in a manner dependent on the positionof the crankshaft.

It is thus possible for the torque applied, or picked off, at the firstconnecting-rod bearing and at the second connecting-rod bearing by wayof the electromechanical converter, and/or the lateral force therebyapplied to the crankshaft in a direction perpendicular to the crankshaftaxis, to be controlled in a manner dependent on the position of thecrankshaft. The latter are possible in particular if theelectromechanical converters are designed such that the respectivemagnetic field exerts a lateral force on the crankshaft at therespective connecting-rod bearings, in particular if the inner and/orouter magnetic field units do not fully surround the crankshaft butsurround the crankshaft in particular only on one side, in particularwith a surround angle of less than 360° or 270°. This is the case inparticular if the inner magnetic field units each have the shape of acircular-arc-shaped inner ring section which surrounds the respectivecrank webs, and the respective circular-arc-shaped inner ring sectionextends with a first center angle of less than 360° or 270°, and/or ifthe outer magnetic field units each have the shape of acircular-arc-shaped outer ring section which surrounds the firstcircular path of the first inner magnetic field unit with a radialspacing, and the respective circular-arc-shaped outer ring sectionextends with a second center angle of less than 360° or 270°. Thenon-surrounding section of the magnetic field unit preferably pointstoward the respective piston or away from said piston.

In the case of the crankshaft being incompletely surrounded in this way,the magnetic field units, when outputting power or absorbing power,exert a lateral force on the crankshaft perpendicular to the crankshaftaxis. Said lateral force can be utilized to reduce or compensategenerated inertia forces and torques of relatively high order, inparticular of second order, on the crankshaft. In particular, wobblingtorques which act on the crankshaft in a direction parallel to thereciprocating movement of the pistons, for example in the case of afour-cylinder in-line engine, can be compensated. Therefore, arefinement of the invention provides that the distribution of the poweris performed in a manner dependent on the position of the crankshaft insuch a way that inertia forces and torques of relatively high order, inparticular of second order, in particular wobbling torques in adirection perpendicular to the crankshaft axis, arising as a result ofthe movement of the crankshaft, of the at least one first connectingrod, of the at least one second connecting rod, of the first pistonand/or of the second piston are reduced or compensated.

The reciprocating-piston engine according to the invention and thesystems according to the invention will be described in more detailbelow, merely by way of example, on the basis of specific exemplaryembodiments illustrated schematically in the drawings.

In detail, in the drawings:

FIG. 1a shows, in an oblique view, a first exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units and circular-arc-shaped outercoil units;

FIG. 1b shows, in a cross-sectional view from a front elevation, thefirst exemplary embodiment incorporated into a system;

FIG. 1c shows, in a cross-sectional view from a side elevation, thefirst exemplary embodiment with the piston at bottom dead center;

FIG. 1d shows, in a cross-sectional view from a side elevation, thefirst exemplary embodiment with the piston at top dead center;

FIG. 1e shows, in an oblique view, the crankshaft of the first exemplaryembodiment without balancing weights;

FIG. 1f shows, in an oblique view, a balancing weight of the firstexemplary embodiment;

FIG. 1g shows, in an oblique view, the crankshaft of the first exemplaryembodiment with balancing weights;

FIG. 1h shows, in an oblique view, the crankshaft of the first exemplaryembodiment with balancing weights and the ring-shaped inner permanentmagnet units;

FIG. 1i shows, in an oblique view, the ring-shaped inner permanentmagnet unit of the first exemplary embodiment with first permanentmagnets arranged adjacent to one another with north poles pointing in acommon circumferential direction;

FIG. 1j shows, in an oblique view, the circular-arc-shaped outer coilunit of the first exemplary embodiment, having a second center angle of180°, with a second coil with a second coil axis running parallel to thecrankshaft axis;

FIG. 2a shows, in an oblique view, a first alternative embodiment of thecrankshaft with circular-arc-shaped inner permanent magnet units with afirst center angle of 180°;

FIG. 2b shows, in an oblique view, the circular-arc-shaped innerpermanent magnet unit of the first alternative embodiment of thecrankshaft with a first center angle of 180°;

FIG. 3a shows, in an oblique view, a second exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units and circular-arc-shaped outercoil units;

FIG. 3b shows, in an oblique view, the crankshaft of the secondexemplary embodiment with balancing weights and with the ring-shapedinner permanent magnet units;

FIG. 3c shows, in an oblique view, the ring-shaped inner permanentmagnet unit of the second exemplary embodiment with adjacently arrangedfirst permanent magnets with poles of alternating polarity orientationpointing in a radial direction;

FIG. 3d shows, in an oblique view, the circular-arc-shaped outer coilunit of the second exemplary embodiment, having a second center angle of180°, with a second coil with a second coil axis running in acircle-circumferential direction;

FIG. 4a shows, in an oblique view, a third exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units and closed ring-shaped outercoil units;

FIG. 4b shows, in an oblique view, the crankshaft of the third exemplaryembodiment with balancing weights and with the ring-shaped innerpermanent magnet units;

FIG. 4c shows, in an oblique view, the ring-shaped inner permanentmagnet unit of the third exemplary embodiment with adjacently arrangedfirst permanent magnets with poles of alternating polarity orientationpointing in a radial direction;

FIG. 4d shows, in a cross-sectional view from a side elevation, thering-shaped outer coil unit of the third exemplary embodiment, havingsecond coils which are arranged in a line with one another in acircle-circumferential direction and which have second coil axes runningradially in relation to the crankshaft axis;

FIG. 5a shows, in an oblique view, a fourth exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units and closed ring-shaped outercoil units;

FIG. 5b shows, in an oblique view, the ring-shaped outer coil unit ofthe fourth exemplary embodiment with a second coil with a second coilaxis running parallel to the crankshaft axis;

FIG. 6 shows, in a cross-sectional view from a side elevation, a secondalternative embodiment having a ring-shaped inner coil unit with firstcoils which are arranged in a line with one another in acircle-circumferential direction and which have first coil axes runningradially in relation to the crankshaft axis, and having a ring-shapedouter permanent magnet unit with adjacently arranged second permanentmagnets which have poles of alternating polarity orientation pointing ina radial direction;

FIG. 7a shows, in a cross-sectional view from a side elevation, a thirdalternative embodiment having a ring-shaped inner coil unit with firstcoils which are arranged in a line with one another in acircle-circumferential direction and which have first coil axes runningradially in relation to the crankshaft axis, and having a ring-shapedouter coil unit with second coils which are arranged in a line with oneanother in a circle-circumferential direction and which have second coilaxes running radially in relation to the crankshaft axis; and

FIG. 7b shows, in a cross-sectional illustration A-A from FIG. 7a , anadditional coil, which is connected to a first coil, of the inner coilunit, and a lateral coil.

Since the figures show, in part, the same exemplary embodiment fromdifferent views and in different degrees of detail, and the exemplaryembodiments, in part, differ only by certain features, the followingdescription of the figures will, in part, not provide a repeatedexplanation of reference designations and features that have alreadybeen mentioned previously, and, in part, only the differences betweenthe individual exemplary embodiments will be discussed.

FIGS. 1a to 1j illustrate a first exemplary embodiment of thereciprocating-piston engine according to the invention from differentviews and in different degrees of detail. Said figures will be discussedjointly below.

The reciprocating-piston engine of the first exemplary embodiment is afour-cylinder in-line engine which operates on the basis of theOtto-cycle engine principle, as shown in figures la and lb. Thereciprocating-piston engine is assembled substantially from a cylinderblock 1, a crank chamber 2 which is formed partially in the cylinderblock 1 and which is delimited at the bottom by an oil pan 52, acrankshaft 3, and four pistons 27 and 31, which are connected to thecrankshaft 3 by way of four connecting rods 5 and 32. Below, forsimplicity, a partial description will be given of only the first piston27 and the second piston 31 and the peripherals thereof.

The crankshaft 3 is arranged within the crank chamber 2, so as to berotatable about a geometric crankshaft axis 4, in a total of five mainbearings 44 a and 44 b, and is held there by way of five bearing covers49, which are fixed to the cylinder block 1 by way of bearing coverscrews 50, as illustrated in FIG. 1 a.

The crankshaft 3 is formed in one piece from a magnetizable material.

The first connecting rod 5 is mounted rotatably in a firstconnecting-rod bearing 6 of the crankshaft 3 and, during rotation of thecrankshaft 3, performs a connecting-rod movement in a geometricconnecting-rod movement space 7. The first piston 27 is mounted in aconnecting-rod eye of the first connecting rod 5, as shown in FIGS. 1aand 1 b.

The second connecting rod 32 is mounted rotatably in a secondconnecting-rod bearing 33 of the crankshaft 3 and, during rotation ofthe crankshaft 3, likewise performs a connecting-rod movement in ageometric connecting-rod space.

The same applies to the further connecting rods, connecting-rod bearingsand pistons. Below, the arrangement thereof will be described, in part,merely on the basis of the first connecting rod 5, the firstconnecting-rod bearing 6 and the first piston 27.

The first connecting-rod bearing 6 of the crankshaft 3 is connected viaa first crank web 9 a to the adjacent first main bearing 44 a and via asecond crank web 9 b, which is situated opposite the first crank web 9a, to the second main bearing 44 b, wherein the crank webs 9 a and 9 bgive rise to the radial offset of the first connecting-rod bearing 6 inrelation to the crankshaft axis 4, as shown in FIG. 1 e.

The first crank web 9 a has a first fastening surface 13 a on a sidewhich points radially outward in relation to the crankshaft axis 4 andwhich is situated opposite the first connecting-rod bearing 6. Also, thesecond crank web 9 b has a second fastening surface 13 b on a side whichpoints radially outward in relation to the crankshaft axis 4 and whichis situated opposite the first connecting-rod bearing 6, as illustratedin FIG. 1 e. The fastening surfaces 13 a and 13 b, which are situatedopposite the first connecting-rod bearing 6, are planar and lie in acommon plane. Correspondingly, in each case two fastening surfaces arealso situated opposite the other connecting-rod bearings of thecrankshaft 3, such as for example the third fastening surface 13 csituated opposite the second connecting-rod bearing 33 on the thirdcrank web 9 c, and the fourth fastening surface 13 c situated oppositethe second connecting-rod bearing 33 on the fourth crank web 9 d,corresponding to FIG. 1 e.

A first balancing weight 14 a is fixed in positively locking fashion ina radial direction to the first fastening surface 13 a, a secondbalancing weight 14 b is fixed in positively locking fashion in a radialdirection to the second fastening surface 13 b, a third balancing weight14 c is fixed in positively locking fashion in a radial direction to thethird fastening surface 13 c, and a fourth balancing weight 14 d isfixed in positively locking fashion in a radial direction to the fourthfastening surface 13 d. The same applies to the other fasteningsurfaces. The positively locking fixing of the balancing weights 14 a,14 b, 14 c and 14 d to the fastening surfaces 13 a, 13 b, 13 c and 13 dis realized in each case by way of two balancing-weight screws 45,wherein the respective balancing weight 14 a, 14 b, 14 c and 14 d iscentered on the respective fastening surface 13 a, 13 b, 13 c and 13 dby way of a centering bolt 46, as shown in FIGS. 1f and 1 g. Thebalancing weights 14 a, 14 b, 14 c and 14 d are, like the otherbalancing weights, composed of a non-magnetizable material, for examplecast iron, high-grade steel, carbon fiber, a ceramic material oraluminum. All of the balancing weights correspond to one another.

A first inner magnetic field unit 8 a is arranged on a side, whichpoints radially outward in relation to the crankshaft axis 4, of thefirst balancing weight 14 a. Thus, the first inner magnetic field unit 8a is arranged, indirectly via the first balancing weight 14 a, on thefirst crank web 9 a, which is axially adjacent to the firstconnecting-rod bearing 6, of the crankshaft 3, as shown in FIGS. 1b and1 h.

Corresponding to this arrangement, a second inner magnetic field unit 8b is arranged on the second crank web 9 b, which is axially adjacent tothe first connecting-rod bearing 6 and situated axially opposite thefirst crank web 9 a, of the crankshaft 3 by virtue of the second innermagnetic field unit 8 b being fixed to that side of the second balancingweight 14 b which points radially outward.

Accordingly, inner magnetic field units, for example a third magneticfield unit 8 c, are also arranged on the other balancing weights, as islikewise shown in FIGS. 1b and 1 h.

The inner magnetic field units 8 a, 8 b and 8 c are in each case pushedinto a first linear guide 17 a or second linear guide 17 b or thirdlinear guide 17 c, respectively, which extends in an axial direction,that is to say parallel to the crankshaft axis 4, on the respectivebalancing weight 14 a or 14 b or 14 c, and are fixed axially there suchthat said inner magnetic field units cannot be displaced, as is shown inFIGS. lb and 1 h. The linear guides 17 a, 17 b and 17 c fix therespective inner magnetic field unit 8 a, 8 b or 8 c in a radialdirection in relation to the crankshaft axis 4, that is to say outwardin a centrifugal direction, and in a circumferential direction, that isto say rotationally, in positively locking fashion by way of anundercut. A detailed view of the first linear guide 17 a, which isformed in the first inner magnetic field unit 8 a and the firstbalancing weight 14 a, is shown in FIGS. 1f, 1g and 1i . The secondlinear guide 17 b of the second balancing weight 14 b is shown in FIG. 1g.

The first inner magnetic field units 8 a, 8 b and 8 c have the shape ofa closed circular inner ring which surrounds the respective crank web 9a, 9 b or 9 c and which has a geometric first axis 15 which lies on thecrankshaft axis 4. In other words, said first inner magnetic field unitshave the shape of a circular-arc-shaped inner ring section whichsurrounds the respective crank web 9 a, 9 b or 9 c and which has acommon geometric first axis 15 which lies on the crankshaft axis 4,wherein the circular-arc-shaped inner ring section extends with a firstcenter angle αof 360°, such that the respective circular arc is closedto form a ring, as shown in FIG. 1 i.

For better stabilization of all of the ring-shaped inner magnetic fieldunits 8 a, 8 b and 8 c, these are each connected to the respectiveconnecting-rod bearing 6 by way of stabilizing bolts 47, FIG. 1 g.

All of the inner magnetic field units, eight inner magnetic field unitsin the present exemplary embodiment, correspond to one another, FIG. 1h.

The inner magnetic field units 8 a, 8 b and 8 c are permanently magneticand are each in the form of an inner permanent magnet unit 8 a, 8 b and8 c respectively. Accordingly, the first inner permanent magnet unit 8 ahas, in relation to the crankshaft axis 4, a multiplicity of firstpermanent magnets 16 arranged in a line with one another in acircle-circumferential direction, wherein said first permanent magnets16 are arranged adjacent to one another along the circular inner ringand have north poles N pointing in a common circumferential direction,such that the magnetic polarity of the first permanent magnets 16alternates in the circle-circumferential direction, such that a magneticalternating field is generated during rotation of the crankshaft 3, asshown in FIG. 1i . In other words, the permanent magnet units 8 a, 8 band 8 c are formed by magnet rings which, along the ring circumference,have a multiplicity of alternating magnetic north poles N and southpoles S, such that north poles N and south poles S alternate with oneanother in the circle-circumferential direction.

Thus, the first inner magnetic field unit 8 a, the second inner magneticfield unit 8 b and the third inner magnetic field unit 8 c pointradially outward in relation to the crankshaft axis 4. Furthermore,during rotation of the crankshaft 3, said inner magnetic field unitscirculate around the crankshaft axis 4, in each case on a geometriccircular path which is axially adjacent to the connecting-rod movementspace 7; specifically, the first inner magnetic field unit 8 acirculates on the first circular path 10 a, and the second innermagnetic field unit 8 b circulates on the second circular path 10 b, asshown in FIGS. 1b and 1 h.

The connecting-rod movement space 7 of the first connecting rod 5 issituated in the axial intermediate space between the first circular path10 a and the second circular path 10 b, as indicated in FIG. 1b . Thisapplies correspondingly to the other connecting rods.

A first outer magnetic field unit 11 a is arranged in static fashion inthe crank chamber 2 so as to be radially spaced apart from the firstcircular path 10 a of the ring-shaped first inner permanent magnet unit8 a. A second outer magnetic field unit 11 b is provided, likewise instatic fashion, in the crank chamber 2 so as to be parallel to andspaced apart from the first outer magnetic field unit 11 a, which secondouter magnetic field unit surrounds the second circular path 10 b of thering-shaped second inner permanent magnet unit 8 b with a radialspacing, as indicated in figures 1a, 1b, 1c and 1d . Accordingly, eachinner permanent magnet unit is assigned an outer magnetic field unit.

All of the outer magnetic field units 11 a, 11 b, 11 c and 11 d have theshape of a circular-arc-shaped outer ring section which surrounds therespective circular path of the respective inner magnetic field unit 8a, 8 b, 8 c and 8 d and which has a geometric second axis 18 which lieson the crankshaft axis 4, FIGS. 1a, 1c, 1d and 1j . Said respectivecircular-arc-shaped outer ring section has a second center angle β of180°, as illustrated in FIG. 1 j.

All of the outer magnetic field units 11 a, 11 b, 11 c and lid areelectromagnetic and are in the form of outer coil units 11 a, 11 b, 11 cand lid respectively. These have in each case one second coil 19 c, thesecond coil axis 20 c of which runs parallel to the crankshaft axis 4,FIG. 1 j.

The first inner permanent magnet unit 8 a and the first outer coil unit11 a are thus arranged and designed such that, together, they form afirst electromechanical converter 12 a. During rotation of thecrankshaft 3 and thus also of the first inner permanent magnet unit 8 a,a magnetic alternating field is generated in the first outer coil unit11 a, whereby an alternating voltage is induced in the second coil 19 c.Said voltage may for example be utilized for charging an electricalenergy store. The first electromechanical converter 12 a is, in thiscase, an electrical generator.

Conversely, by application of an alternating voltage to the second coil19 c of the first outer coil unit 11 a, a magnetic force can be exertedon the first inner permanent magnet unit 8 a, such that the first innerpermanent magnet unit 8 a and thus also the crankshaft 3 can be set inrotation. In this case, the first electromechanical converter 12 a formsan electric motor.

A corresponding situation applies to the second inner permanent magnetunit 8 a and the second outer coil unit 11 a, to the third innerpermanent magnet unit 8 a and the third outer coil unit 11 a, and to thefourth inner permanent magnet unit 8 a and the fourth outer coil unit 11a, which form a second electromechanical converter 12 b, a thirdelectromechanical converter 12 c and a fourth electromechanicalconverter 12 d respectively.

The reciprocating-piston engine has an electrically actuable variableoutlet valve drive 24 for a first outlet valve 25 which is assigned to afirst combustion chamber 26 of the first piston 27, and for each furtheroutlet valve of the other pistons. The variable outlet valve drive 24 isdesigned such that the first outlet valve 25 and each further outletvalve can be opened independently of the position of the crankshaft 3.

The reciprocating-piston engine is incorporated into a system which isschematically indicated in FIG. 1b and which comprises a chargeable anddischargeable electrical energy store 21, an electrical control unit 22,an electrical power control element 30, and a crankshaft sensor 23 fordetecting an angular position of the crankshaft 3.

The control unit 22 is electrically interconnected with the electricalenergy store 21, with the first electromechanical converter 12 a, withthe second electromechanical converter 12 b and with all furtherelectromechanical converters. Furthermore, the control unit 22 isdesigned such that the reciprocating-piston engine can be switchedbetween an electric-motor operating mode and a generator operating mode.In the electric-motor operating mode, the crankshaft 3 is driven withelectric motor action by virtue of the electrical energy store 21 beingdischarged. In the generator operating mode, the electrical energy storeis charged by virtue of the crankshaft 3 being mechanically driven, forexample by virtue of the crankshaft 3 being driven with combustionengine action by way of the reciprocating-piston engine, or by virtue ofthe crankshaft 3 being driven by external action.

The control unit 22 is interconnected with the crankshaft sensor 23 andwith the variable outlet valve drive 24, and is designed, such that, inthe electric-motor operating mode, the first outlet valve 25 is open ina position range 28 of the crankshaft 3 in which the first piston 27 issituated in a compression stroke 29, illustrated by the arrows 28 and 29in FIG. 1 c. The compression stroke in that position range 28 of thecrankshaft 3 in which the first piston 27 performs a movement 29 frombottom dead center of the first piston 27, illustrated in FIG. 1 c, inthe direction of top dead center of the first piston 27, illustrated inFIG. 1 d. A corresponding situation applies to the other pistons and tothe outlet valves assigned thereto.

By way of said measure, it is achieved that, in the electric-motoroperating mode, no compression has to take place in the respectivecombustion chamber 26, and the drag torque of the reciprocating-pistonengine can be reduced.

The power control element 30 is electrically interconnected with theelectrical energy store 21, with the first electromechanical converter12 a, with the second electromechanical converter 12 b, with the thirdelectromechanical converter 12 c, with the fourth electromechanicalconverter 12 d, and with each further electromechanical converter. Thepower control element 30 is furthermore designed such that, in theelectric-motor operating mode, the crankshaft 3 can be driven withelectric motor action with adjustable power by virtue of the electricalenergy store 21 being discharged, and in the generator operating mode,the electrical energy store 21 can be charged with adjustable power byvirtue of the crankshaft 3 being mechanically driven.

The power control element 30 may be a functional constituent part of thecontrol unit 22 and vice versa.

The power control element 30 is electrically interconnected with theelectrical energy store 21, with all of the electromechanical convertersand with the crankshaft sensor 23, and designed, such that the power canbe distributed to the electromechanical converter pairs 12 a and 12 b,12 c and 12 d etc., which are assigned to in each case one piston, withdifferent power fractions, such that the pistons can be assigneddifferent levels of electrical power. The distribution of the power tothe converter pairs 12 a and 12 b, 12 c and 12 d, etc., is performed ina manner dependent on the position of the crankshaft 3. In particular,the distribution of the power is performed in a manner dependent on theposition of the crankshaft 3, in such a way that inertia forces andinertia torques of relatively high order, in particular of second order,arising as a result of the movement of the crankshaft 3, of all of theconnecting rods and of all of the pistons, are reduced or compensated,as described in the introduction.

FIGS. 2a and 2b illustrate a first alternative embodiment of thecrankshaft 3. In this alternative embodiment, instead of the shape of aclosed circular inner ring which surrounds the respective crank web 9 a,9 b, 9 c and 9 d, as in the first embodiment of FIGS. 1a to 1 j, allinner permanent magnet units 8 a, 8 b, 8 c and 8 d have the shape of acircular-arc-shaped inner ring section which surrounds the respectivecrank web. Said open ring section has a semicircular shape with ageometric first axis 15 which lies on the crankshaft axis 4. Thus, thecircular-arc-shaped inner ring section has a first center angle α of180°, as shown in FIGS. 2a and 2b . During rotation of the crankshaft 3,the inner permanent magnet units 8 a and 8 b circulate around thecrankshaft axis 4 on geometric first circular paths 10 a and 10 brespectively, which are illustrated by way of dashed lines in FIG. 2 a.

FIGS. 3a to 3d show a second exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units 8 a, 8 b, 8 c and 8 d, andcircular-arc-shaped outer coil units 11 a, 11 b, 11 c and 11 d.

As is also the case in the preceding, first exemplary embodiment ofFIGS. la to 1 j, the inner magnetic field units are permanently magneticand are in the form of first inner permanent magnet units 8 a, 8 b, 8 cand 8 d. The latter are each in the shape of a closed circular innerring which surrounds the respective crank web.

In this exemplary embodiment, too, the inner permanent magnet units 8 a,8 b, 8 c and 8 d have first permanent magnets 16 which are arranged in aline with one another in a circle-circumferential direction in relationto the crankshaft axis 4, in such a way that the magnetic polarity ofthe first permanent magnets 16 alternates in the circle-circumferentialdirection, such that a magnetic alternating field is generated duringrotation of the crankshaft 3. However, the orientation of the permanentmagnets 16 differs in relation to the preceding exemplary embodiments.In this exemplary embodiment, the first permanent magnets are arrangedadjacent to one another along the circular inner ring section and havealternating magnetic north poles N and south poles S pointing in aradial direction, as shown in FIG. 3 c.

The outer magnetic field units are electromagnetic and are in the formof outer coil units 11 a, 11 b, 11 c and 11 d. They have the shape of acircular-arc-shaped outer ring section which surrounds the respectivecircular path 10 a and 10 b of the inner permanent magnet units 8 a and8 b with a radial spacing and which has a geometric second axis 18 whichlies on the crankshaft axis 4, wherein the circular-arc-shaped outerring section extends with a second center angle β of 180°, as shown inFIG. 3 d.

The outer coil units have a second coil 19 b which extends in thecircle-circumferential direction and the second ring-shaped coil axis 20b of which runs in the circle-circumferential direction, as shown inFIG. 3d . As is likewise shown in FIG. 3d , in each case two outer coilunits 11 a and 11 b are assembled in one housing, wherein the respectivesecond coils 19 b of the two outer coil units 11 a and 11 b are formedby a common, assembled second coil 19 b.

The third exemplary embodiment of the reciprocating-piston engineaccording to the invention as illustrated in FIGS. 4a to 4d likewise hasclosed ring-shaped inner permanent magnet units 8 a, 8 b, 8 c and 8 dwith the geometric first axis 15, but has closed ring-shaped outer coilunits 11 a, 11 b, 11 c and 11 d.

As in the second exemplary embodiment from FIGS. 3a to 3d , the innerpermanent magnet units 8 a, 8 b, 8 c and 8 d have first permanentmagnets 16 which are arranged in a line with one another in acircle-circumferential direction in relation to the crankshaft axis 4,in such a way that the magnetic polarity of the first permanent magnets16 alternates in the circle-circumferential direction, such that amagnetic alternating field is generated during rotation of thecrankshaft 3. The first permanent magnets 16 are arranged adjacent toone another along the circular inner ring section and have alternatingmagnetic north poles N and south poles S pointing in a radial direction,as shown in FIG. 4c .

The outer coil units 11 a, lib, 11 c and 11 d have the shape of acircular-arc-shaped outer ring section which surrounds the respectivecircular path 10 a and 10 b of the respective inner permanent magnetunit 8 a, 8 b, 8 c and 8 d with a radial spacing and which has ageometric second axis 18 which lies on the crankshaft axis 4, whereinthe circular-arc-shaped outer ring section extends with a second centerangle β of 360°, such that the outer coil units 11 a, 11 b, 11 c and 11d have the shape of a closed circular outer ring which surrounds therespective circular path 10 a and 10 b of the respective inner magneticfield unit 8 a, 8 b, 8 c and 8 d with a radial spacing, as shown inFIGS. 4a and 4 d.

FIG. 4d illustrates the first outer coil units 11 a in more detail. Ithas second coils 19 a arranged in a line with one another in acircle-circumferential direction and the second coil axes 20 a of whichrun radially in relation to the crankshaft axis 4, such that said secondcoil axes intersect at a common point which lies on the second axis 18,which coincides with the crankshaft axis 4.

FIGS. 5a and 5b show a fourth exemplary embodiment of thereciprocating-piston engine according to the invention with closedring-shaped inner permanent magnet units 8 a, 8 b, 8 c and 8 d and withclosed ring-shaped outer coil units 11 a, lib, 11 c and 11 d.

As shown in FIG. 5b , the ring-shaped first outer coil unit 11 a of thefourth exemplary embodiment has a second coil 19 d with a second coilaxis 20 d which runs parallel to the crankshaft axis 4 and which lies onthe second axis 18. Said second coil 19 d fully surrounds the innerpermanent magnet unit 8 a. The other inner permanent magnet units andouter coil units are constructed in the same way as the first innerpermanent magnet unit 8 a and the first outer coil unit 11 arespectively.

The ring-shaped first outer coil unit 11 a with the second coil 19 d hasa bracket 51 by way of which the first outer coil unit 11 a is helddirectly on the bearing cover 49, which is fixed by way of bearing coverscrews 50 to the cylinder block 1, as shown in FIGS. 5a and 5 b.

In the exemplary embodiments presented above, the inner magnetic fieldunit is formed in each case by an inner permanent magnet unit, and theouter magnetic field unit is formed in each case by an outer coil unit.It is however also possible for the inner magnetic field unit to be aninner coil unit and for the outer magnetic field unit to be an outerpermanent magnet unit, as illustrated in FIG. 6, or an outer coil unit,corresponding to FIG. 7.

FIG. 6 illustrates a second alternative embodiment in which the firstinner magnetic field unit, which has the shape of a closed circularinner ring with a first axis 15 which lies on the crankshaft axis 4, iselectromagnetic and is in the form of a first inner coil unit 34. Thefirst inner coil unit 34 has first coils 35 which are arranged in a linewith one another in a circle-circumferential direction in relation tothe crankshaft axis 4 and the first coil axes 36 of which run radiallyin relation to the crankshaft axis 4.

The first outer magnetic field unit has the shape of a closed circularouter ring with a second axis 18 which lies on the crankshaft axis 4,and said first outer magnetic field unit is permanently magnetic and isin the form of a first outer permanent magnet unit 37. The first outerpermanent magnet unit 37 has second permanent magnets 43 which arearranged in a line with one another in a circle-circumferentialdirection in relation to the crankshaft axis 4, in such a way that themagnetic polarity of the second permanent magnets alternates in thecircle-circumferential direction such that a magnetic alternating fieldis generated during rotation of the crankshaft 3. For this purpose, thesecond permanent magnets 43 are arranged adjacent to one another alongthe circular-arc-shaped inner ring section and have north poles N andsouth poles S of alternating polarity orientation pointing in a radialdirection.

FIGS. 7a and 7b show a third alternative embodiment of the inner andouter magnetic field units. Whereas it has previously been the case thateither the inner or the outer magnetic field unit is formed by apermanent magnet unit, the third alternative embodiment provides thatboth units are coil units. In this way, the use of permanent magnets canbe dispensed with entirely.

As is also the case in the embodiment of FIG. 6, the first innermagnetic field unit has the shape of a closed circular inner ring with afirst axis 15 which lies on the crankshaft axis 4. Furthermore, thefirst inner magnetic field unit is electromagnetic and is in the form ofa first inner coil unit 34. The first inner coil unit 34 has first coils35 which are arranged in a line with one another in acircle-circumferential direction in relation to the crankshaft axis 4and the first coil axes 36 of which run radially in relation to thecrankshaft axis 4 and intersect at the first axis 15.

The first coils 35 are arranged and interconnected such that themagnetic polarity, that is to say the north poles N and south poles S,of the first coils 35 alternates in the circle-circumferentialdirection, such that a magnetic alternating field is generated duringrotation of the crankshaft 3.

The first outer coil unit 11 a has the shape of a circular outer ringwhich surrounds the first inner coil unit 34 with a radial spacing andwhich has a geometric second axis 18 which lies on the crankshaft axis4.

The first outer coil unit 11 a has second coils 19 a which are arrangedin a line with one another in a circle-circumferential direction and thesecond coil axes 20 a of which run radially in relation to thecrankshaft axis 4, such that said coil axes intersect at a common pointwhich lies on the second axis 18, which coincides with the crankshaftaxis 4.

To supply a voltage to the first inner coil unit 34 such that the firstcoils 35 generate a magnetic alternating field in acircle-circumferential direction during rotation of the crankshaft 3,the first inner coil unit 34 has additional coils 38 which areelectrically connected to the first coils 35. Here, each of the firstcoils 35 is assigned an additional coil 38. The additional coils 38,which are arranged in a line with one another in acircle-circumferential direction, have additional-coil axes 40 which runparallel to the crankshaft axis 4, as shown in FIGS. 7a and 7 b.

Electromagnetic lateral magnetic field units 39 are arranged in staticfashion in the crank chamber 2 axially adjacent to the first circularpath 10 a of the first inner coil unit 34, wherein each additional coilis assigned an electromagnetic lateral magnetic field units 39. Thearrangement in the crank chamber 2 is indicated schematically in FIG. 5aby way of the reference designation 39. The lateral coils 41, which arearranged in a line with one another in a circle-circumferentialdirection, have lateral-coil axes 42 which run parallel to thecrankshaft axis 4. The additional coils 38 and the lateral magneticfield units 39 are arranged in axially opposed positions with respect toone another in relation to the crankshaft axis 4, and designed, suchthat, during rotation of the crankshaft 3 about the crankshaft axis 4,said additional coils and lateral magnetic field units together form anelectrical generator for the supply of electrical voltage to the firstcoils 35. Thus, the first inner coil unit 34, when it rotates, forms amagnetic field for generating an induced voltage in the first outer coilunit 11 a.

According to the invention, the individual features of the illustratedexemplary embodiments and embodiments may be freely combined.

The invention claimed is:
 1. A reciprocating-piston engine, having acylinder block, a crank chamber which is formed at least partially inthe cylinder block, a crankshaft comprises a magnetizable material andis arranged within the crank chamber so as to be rotatable about ageometric crankshaft axis, at least one first connecting rod which ismounted rotatably in a first connecting-rod bearing of the crankshaftand which, during rotation of the crankshaft, performs a connecting-rodmovement in a geometric connecting-rod movement space, a first innermagnetic field unit, said first inner magnetic field unit being arrangedon a first crank web, which is axially adjacent to the firstconnecting-rod bearing in relation to the crankshaft axis, of thecrankshaft in such a way that the first inner magnetic field unit pointsradially outward in relation to the crankshaft axis and, during rotationof the crankshaft, circulates around the crankshaft axis on a geometricfirst circular path which is axially adjacent to the connecting-rodmovement space, and a first outer magnetic field unit which is arrangedin static fashion in the crank chamber so as to be radially spaced apartfrom the first circular path, wherein the first inner magnetic fieldunit and the first outer magnetic field unit are arranged and designedsuch that, together, they form a first electromechanical converter, anelectric motor or an electrical generator, wherein, the first crank webhas a first fastening surface on a side which points radially outward inrelation to the crankshaft axis and which is situated opposite the firstconnecting-rod bearing, a first balancing weight is fixed in positivelylocking fashion in a radial direction to the first fastening surface,the first balancing weight comprises a non-magnetizable material, andthe first inner magnetic field unit is arranged on a side, which pointsradially outward in relation to the crankshaft axis, of the firstbalancing weight.
 2. The reciprocating-piston engine as claimed in claim1, wherein, the first inner magnetic field unit is pushed into a firstlinear guide, which extends in an axial direction and which fixes thefirst inner magnetic field unit in positively locking fashion in aradial direction and circumferential direction in relation to thecrankshaft axis, on the first balancing weight and is fixed axiallythere.
 3. The reciprocating-piston engine as claimed in claim 1,wherein, the first balancing weight comprises at least one, orcombinations, of the following non-magnetizable materials: cast-iron,austenitic cast iron, gray cast iron; high-grade steel; carbon fiber,sintered carbon fiber; ceramic material; aluminum.
 4. Thereciprocating-piston engine as claimed in any one of claims 1, wherein,the first inner magnetic field unit has the shape of acircular-arc-shaped inner ring section which surrounds the first crankweb and which has a geometric first axis which lies on the crankshaftaxis, and, the circular-arc-shaped inner ring section extends with afirst center angle (α) of greater than 135°.
 5. The reciprocating-pistonengine as claimed in claim 4, wherein, the circular-arc-shaped innerring section extends with a first center angle (α) of 360°, and thefirst inner magnetic field unit has the shape of a closed circular innerring surrounding the first crank web.
 6. The reciprocating-piston engineas claimed in any one of claims 1, wherein, the first outer magneticfield unit has the shape of a circular-arc-shaped outer ring sectionwhich surrounds the first circular path of the first inner magneticfield unit with a radial spacing and which has a geometric second axiswhich lies on the crankshaft axis, and, the circular-arc-shaped outerring section extends with a second center angle (β) of greater than135°.
 7. The reciprocating-piston engine as claimed in claim 6, wherein,the circular-arc-shaped outer ring section extends with a second centerangle (β) of 360°, and the first outer magnetic field unit has the shapeof a closed circular outer ring which surrounds the first circular pathof the first inner magnetic field unit with a radial spacing.
 8. Thereciprocating-piston engine as claimed in any one of claims 1, wherein,the first inner magnetic field unit is permanently magnetic and is inthe form of a first inner permanent magnet unit.
 9. Thereciprocating-piston engine as claimed in claim 8, wherein, the firstinner permanent magnet unit has first permanent magnets arranged in aline with one another in a circle-circumferential direction in relationto the crankshaft axis, in such a way that the magnetic polarity of thefirst permanent magnets alternates in the circle-circumferentialdirection such that a magnetic alternating field is generated duringrotation of the crankshaft, wherein, the first permanent magnets arearranged adjacent to one another, along the circular-arc-shaped innerring section, and have north poles (N) pointing in a commoncircumferential direction, or the first permanent magnets are arrangedadjacent to one another, along the circular-arc-shaped inner ringsection, and have poles (N, S) of alternating polarity orientationpointing in a radial direction.
 10. The reciprocating-piston engine asclaimed in any one of claims 1, wherein, the first inner magnetic fieldunit is electromagnetic and is in the form of a first inner coil unit.11. The reciprocating-piston engine as claimed in claim 10, wherein, thefirst inner coil unit has first coils which are arranged in a line withone another in a circle-circumferential direction in relation to thecrankshaft axis, the first coil axes of which first coils run radiallyin relation to the crankshaft axis, wherein, the first coils arearranged and/or interconnected such that the magnetic polarity of thefirst coils alternates in the circle-circumferential direction, suchthat a magnetic alternating field is generated during rotation of thecrankshaft, or at least one first coil which extends in acircle-circumferential direction and the first coil axis of which runsin the circle-circumferential direction, or at least one first coil, thefirst coil axis of which runs parallel to the crankshaft axis.
 12. Thereciprocating-piston engine as claimed in claim 11, wherein, the firstinner coil unit has at least one additional coil which is electricallyconnected to the at least one first coil, a permanently magnetic orelectromagnetic lateral magnetic field unit is arranged in staticfashion in the crank chamber (2) axially adjacent to the first circularpath of the first inner coil unit, and the at least one additional coiland the lateral magnetic field unit are arranged relative to oneanother, in axially opposed positions with respect to one another inrelation to the crankshaft axis, and designed, such that, duringrotation of the crankshaft about the crankshaft axis, said at least oneadditional coil and lateral magnetic field unit together form anelectrical generator for the supply of electrical voltage to the atleast one first coil.
 13. The reciprocating-piston engine as claimed inclaim 12, wherein, the at least one additional coil has anadditional-coil axis running parallel to the crankshaft axis, or the atleast one additional coil is formed by multiple additional coilsarranged in a line with one another in a circle-circumferentialdirection, with additional coil axes running parallel to the crankshaftaxis, wherein, the lateral magnetic field unit is electromagnetic and isformed by multiple lateral coils arranged in a line with one another ina circle-circumferential direction, with lateral-coil axes runningparallel to the crankshaft axis.
 14. The reciprocating-piston engine asclaimed in any one of claims 1, wherein, the first outer magnetic fieldunit is electromagnetic and is in the form of a first outer coil unit.15. The reciprocating-piston engine as claimed in claim 14, wherein, thefirst outer coil unit has second coils which are arranged in a line withone another in a circle-circumferential direction and the second coilaxes of which run radially in relation to the crankshaft axis, or atleast one second coil which extends in a circle-circumferentialdirection and the second coil axis of which runs in thecircle-circumferential direction, or at least one second coil, thesecond coil axis of which runs parallel to the crankshaft axis.
 16. Thereciprocating-piston engine as claimed in claim 10, wherein, the firstouter magnetic field unit is permanently magnetic and is in the form ofa first outer permanent magnet unit.
 17. The reciprocating-piston engineas claimed in claim 16, wherein, the first outer permanent magnet unithas second permanent magnets arranged in a line with one another in acircle-circumferential direction in relation to the crankshaft axis, insuch a way that the magnetic polarity of the second permanent magnetsalternates in the circle-circumferential direction such that a magneticalternating field is generated during rotation of the crankshaft,wherein, the second permanent magnets are arranged adjacent to oneanother along the circular-arc-shaped inner ring section, and have northpoles (N) pointing in a common circumferential direction, or the secondpermanent magnets are arranged adjacent to one another along thecircular-arc-shaped inner ring section, and have poles (N, S) ofalternating polarity orientation pointing in a radial direction.
 18. Thereciprocating-piston engine as claimed in any one of claims 1, furthercomprising: a second inner magnetic field unit, said second innermagnetic field unit being arranged on a second crank web, which isaxially adjacent to the first connecting-rod bearing and which issituated axially opposite the first crank web, of the crankshaft in sucha way that the second inner magnetic field unit points radially outwardin relation to the crankshaft axis and, during rotation of thecrankshaft, circulates around the crankshaft axis on a geometric secondcircular path which is axially adjacent to the connecting-rod movementspace, and a second outer magnetic field unit which is arranged instatic fashion in the crank chamber so as to be radially spaced apartfrom the second circular path, in such a way that the second outermagnetic field unit and the second inner magnetic field unit togetherform a second electromechanical converter, wherein the connecting-rodmovement space of the at least one first connecting rod extends in anaxial intermediate space between the first circular path and the secondcircular path, the second crank web has a second fastening surface on aside which points radially outward in relation to the crankshaft axisand which is situated opposite the first connecting-rod bearing, asecond balancing weight is fixed in positively locking fashion in aradial direction to the second fastening surface, the second balancingweight comprises a non-magnetizable material, and the second innermagnetic field unit is arranged on a radially outwardly pointing side ofthe second balancing weight, wherein, the second inner magnetic fieldunit corresponds to the first inner magnetic field unit, and/or thesecond outer magnetic field unit corresponds to the first outer magneticfield unit, and/or the second balancing weight corresponds to the firstbalancing weight.
 19. A system comprising: the reciprocating-pistonengine as claimed in claim 1, a chargeable and dischargeable electricalenergy store, an electrical control unit, and a crankshaft sensor fordetecting a position of the crankshaft, wherein the control unit iselectrically interconnected with the electrical energy store, with thefirst electromechanical converter and with the second electromechanicalconverter, and designed, such that the reciprocating-piston engine canbe switched between an electric-motor operating mode, in which thecrankshaft can be driven with electric motor action by virtue of theelectrical energy store being discharged, and a generator operatingmode, in which the electrical energy store can be charged by virtue ofthe crankshaft being mechanically driven, by virtue of the crankshaftbeing driven with combustion engine action by way of thereciprocating-piston engine, and the reciprocating-piston engine has anelectrically actuable variable outlet valve drive for at least one firstoutlet valve which is assigned to a first combustion chamber of a firstpiston which is coupled to the at least one first connecting rod, saidelectrically actuable variable outlet valve drive being designed suchthat the at least one first outlet valve can be opened regardless of theposition of the crankshaft, wherein, the control unit is interconnectedwith the crankshaft sensor and with the variable outlet valve drive, anddesigned, such that, in the electric-motor operating mode, the at leastone first outlet valve is opened in a position range of the crankshaftin which the first piston is situated in a compression stroke.
 20. Thesystem, as claimed in claim 19, comprising: the reciprocating-pistonengine, a chargeable or dischargeable electrical energy store, anelectric power control element and a crankshaft sensor for detecting aposition of the crankshaft, wherein the reciprocating-piston engine hasa first piston, which is assigned to the first electromechanicalconverter and to the second electromechanical converter and which iscoupled to the at least one first connecting rod, and a second piston,which is assigned to a third electromechanical converter, the lattercorresponding to the first electromechanical converter, and which iscoupled to at least one second connecting rod which is mounted rotatablyin a second connecting-rod bearing of the crankshaft, and the powercontrol element is electrically interconnected with the electricalenergy store, with the first electromechanical converter and with thethird electromechanical converter, and designed, such that, in anelectric-motor operating mode, the crankshaft can be driven withelectric motor action with adjustable power by virtue of the electricalenergy store being discharged, or, in a generator operating mode, theelectrical energy store can be charged with adjustable power by virtueof the crankshaft being mechanically driven, by virtue of the crankshaftbeing driven with combustion engine action by way of thereciprocating-piston engine, wherein, the power control element iselectrically interconnected with the electrical energy store, with thefirst electromechanical converter, with the third electromechanicalconverter and with the crankshaft sensor, and designed, such that thepower is distributed to the first electromechanical converter with afirst power fraction and to the third electromechanical converter with asecond power fraction, the distribution of the power to the firstelectromechanical converter and to the third electromechanical converteris performed in a manner dependent on the position of the crankshaft,and, the distribution of the power is performed in a manner dependent onthe position of the crankshaft in such a way that inertia forces andtorques of relatively high order, of second order, arising as a resultof the movement of the crankshaft, of the at least one first connectingrod, of the at least one second connecting rod, of the first pistonand/or of the second piston are reduced or compensated.